Some household and car insurance companies vary premiums depending on whether or not an address has a letter after the number, according to new research by consumers’ association Consumentenbond.

It found that one man in The Hague paid €105 more than his neighbour for exactly the same car insurance. The only difference? He lived at number 83A, his neighbour at number 83.

Insurer SNS Reaal declined to comment on the reason behind the difference, citing competition considerations. However, ASR told the association that premiums will differ in a street with different sorts of housing.

The Consumentenbond compared 31 insurers operating in the province of Utrecht and found 17 took general postcodes into account when setting premiums.

Seven of those looked at the micro level, by focusing on the postcode letters and three – SNS Reaal, BLG Wonen and Vivat – went as far as to use letters after a house number to determine the cost.

The Consumentenbond says insurance companies should be more transparent about how they set premiums. ‘Their policies towards risk are very unclear,’ the organisation said. ‘We think they should be based on statistics available to everyone.’